Automatic air conditioning devices have been developed in recent years for automatically opening and closing defusers in response to air conditions in a room. For instance, a product marketed under the trademark THERMA-FUSER.RTM. by Acutherm, Inc. in Novato, Calif. fits on a standard air conditioning duct in place of a standard defuser and automatically changes the defuser discharge opening in response to air temperatures in the room.
Automatic defuser controls of the general type mentioned above have important advantages in providing system flexibility and reducing energy comsumption, but they may create a problem if the system in which they are used is not provided with additional means for making major system adjustments in response to automatic adjustment of many of the THERMA-FUSER.RTM.s. For instance, if a large number of THERMA-FUSER.RTM.s operate to close down their discharge areas at the same time, the resulting reduction in air velocity through supply ducts may cause a substantial increase in duct static pressure and increase velocity and whistling through the defuser.
While a number of air conditioning control units have been provided in the past, none has been provided which offers an efficient and economic solution to this problem.